This invention relates to rising stem valves. These valves have a valve seat that separates an inlet and an outlet passage. The valve seat is arranged to receive a closure element. Extending away from the closure element is a valve stem that is actuated axially to open and close the valve by unseating and seating the closure element. Of course, an actuator passage must be provided in the valve body extending away from the valve seat. In conventional valve designs, the valve stem extends through the valve body and is actuated by elements connected to it outside of the valve body. The stem is surrounded by a ring of rings of packing that maintain the pressure within the valve.
This invention relates to magnetically actuated packless valves for high pressure applications. A related patent that pertains to a magnetically actuated valve, but not especially for high pressure applications, is U.S. Pat. No. 2,289,574. A more or less typical packed rising stem valve is illustrated in U.S. Pat. No. 3,269,698. Aspects of this invention relate to my own U.S. Pat. No. 4,106,825.
The known advantage of magnetically actuated valves is the elimination of the stuffing box or packing which has always been a drawback. However, in the past, magnetically actuated valves have been confined to relatively low pressures if at all used. The principal reason has been that sufficiently strong permanent magnets did not exist that would actuate the magnetic valve through the thick walls required to contain high pressures. Newly available permanent magnets permit the use of thicker walls in the valve housing providing the possibility of magnetically actuated valves for use at high pressures.
It is an object of this invention to provide a magnetically actuated valve for high pressures which will reliably open and close at minimal torques (applied by the drive magnets to the driven magnets) even at pressures in excess of 2000 psi. It is a further object to provide a magnetically actuated rising stem valve that is pressure tight at pressures exceeding 10,000 psi and which can be opened against a sealing pressure of over 10,000 psi. It is a further object of this invention to provide a magnetically actuated valve wherein the closure element floats relative to the stem and wherein relative motion therebetween opens or closes a pilot valve which being of smaller area than the main valve seat may be opened against the same pressure with much less force. It is yet another object of this invention to provide a magnetically actuated valve with a fail-safe manual override.